Kee said fire is a huge concern, especially with how overloaded outlets get. His advice: Pay attention to wattage and make sure it's not going over 200.

"Traditional incandescent strings you can generally go two to three strings to get to that 200 watts and be safe," Kee said. "LED lights are a lot more efficient, you can go up to 14 strings, generally."

Keeping the Christmas tree away from heat sources and keeping them well-watered will help, too.

Doing a crunch test, Kee said, is a good way to see if a tree is getting enough water. A dry tree is going to be even more hazardous with those string lights.

Video from the National Institute of Standards and Technology shows how quickly a very dry tree can ignite, becoming fully engulfed in about five seconds.

Smoke detectors are important to have activated throughout the holiday season. A Nest smoke alarm connects to the person's smartphone.

"You can be anywhere and it will alert you if there's an issue," Kee said.